1. Field of the Invention
The present invention relates generally to energy absorber units mounting a bumper to a vehicle frame, and in particular is concerned with metering pin for metering the flow of fluid between fluid chambers as an energy absorber unit telescopes in response to an impact on the bumper.
2. Description of the Related Art
Energy absorber units for mounting vehicle bumpers are well-known. Many hydraulic energy absorber units employ fixed, longitudinally-extending, metallic metering pins which are centrally welded to an end cap of the unit and which extend into an associated oil flow control orifice to meter fluid between fluid pressure chamber to absorb impact energy. To compensate for manufacturing tolerance variations which can result in an axial misalignment of the centrally fixed metering rod and orifice, conventional units feature radially adjustable orifices. While such constructions have compensated for the metering pin and orifice misalignment, their construction is relatively complex and expensive and requires the metering pin to be welded or otherwise fixed to the unit.
U.S. Pat. No. 3,887,224 titled "Impact Energy Absorber With Radially Adjustable Flow Metering Pin," issued June 3, 1975 and assigned to the present assignee, discloses a moldable metering pin for an energy absorbing unit. In one embodiment, the metering pin or rod is adjustable with respect to the axis of the unit so that it can float in alignment with a fixed fluid flow control orifice In a second embodiment, the pin includes a base constructed from inner and outer support rings and a thin wall portion having concentric corrugations. The base provides a flexible support to permit the radial adjustment of the pin relative to a fixed orifice.
The art continues to seek improvements. In an energy absorber unit, it is desirable to utilize a moldable metering pin to reduce manufacturing and assembly costs. Furthermore, it is desirable to provide an economical, moldable metering pin capable of being press-fitted into a receiving cylinder and capable of performing during impact.